This invention relates to vascular catheters (such as angioplasty catheters) specially adapted for rapid exchange of both the guidewire and the catheter during use. It also relates to the method of using those catheters.
Percutaneous transluminal coronary angioplasty (PTCA) has emerged as the major viable present alternative to bypass surgery for revascularization of stenotic and occluded coronary arteries. Although transluminal angioplasty has application in peripheral artery disease, it is most widely used in the treatment of coronary artery disease. Unlike bypass surgery, percutaneous angioplasty does not require general anesthesia, cutting of the chest wall, extracorporeal perfusion, or transfusion of blood. Percutaneous coronary angioplasty is not only less invasive and less traumatic to the patient, it is also less expensive because the angioplasty patient will have a shorter hospital stay and shorter post-procedure recovery time.
Percutaneous transluminal angioplasty is performed by making a skin puncture with a specially-designed needle in one of the groins, and then introducing a guiding catheter (typically 8 or 9 French size) into the aorta and coronary artery orifice. A smaller caliber catheter which has a built-in inflatable and deflatable balloon of predetermined size and diameter is passed through the guiding catheter which is positioned in the opening of a target artery. This balloon catheter (with the balloon totally deflated by negative pressure) is advanced inside the target artery toward the point of obstruction that needs to be dilated. The guidewire plays an essential role in leading the balloon catheter to the target coronary artery in safety and non-traumatic fashion. With the balloon portion of the catheter properly positioned inside the obstructed segment of the artery, under X-ray fluoroscopic observation, the balloon is inflated by injecting contrast media mixed with saline at a pressure sufficient to overcome the resistance of the arteriosclerotic plaque of the obstructed segment.
By inflating the balloon in the stenosis multiple times over a period of between 10-30 seconds and one or two minutes (allowing blood flow between inflations), the desired dilation of the obstructed segment of the artery can be achieved. When the desired results have been obtained by balloon inflations, the guiding catheter, the balloon catheter (with the balloon completely deflated with negative pressure) and the guidewire are withdrawn from the artery and the patient and the procedure is successfully terminated.
The size and diameter of the balloon to be used in a transluminal angioplasty should be approximately matched to the size and native diameter of the obstructed segment of the artery to be dilated. If the balloon size and diameter is smaller than the native artery, the results of balloon angioplasty are suboptimal, requiring a second dilation with a larger-sized balloon, and if balloon size is too large for the native artery, complications may occur due to arterial wall damage.
During the angioplasty procedure, a guidewire is first advanced into the desired location, after which the angioplasty catheter is advanced over the guidewire. It is sometimes necessary to replace (or exchange) either the guidewire or the balloon catheter during the procedure.
If the balloon is undersized, for example, the catheter must be withdrawn and replaced with a larger balloon catheter in order to permit adequate dilatation of the lesion. With conventional over-the-wire catheters, in which the guidewire lumen extends the entire length of the catheter shaft, a guidewire extension (e.g., 145 cm long) must first be attached to the regular guidewire (e.g. 175 cm long) being used outside the patient before the catheter is withdrawn. This permits the distal end of guidewire to be held in position while the catheter is removed and a new catheter is exchanged. Usually, two to three operators are needed to effect such a catheter exchange.
The catheter disclosed in U.S. Pat. No. 4,762,129 avoids the necessity for extending the guidewire or exchange guidewire (e.g. 300 cm in length) by having a short guidewire lumen that extends substantially only through the distal end of the catheter. This type of catheter is referred to herein as a rapid-exchange catheter. Thus, the guidewire is outside the catheter shaft for much of the catheter length, and is inside the catheter at only the distal end. The catheter can be exchanged without extending the 175 cm regular guidewire, and the exchange can be effected by one or two operators. However, this catheter has a serious drawback of not being able to permit ready exchange of guidewires. In clinical practice, the need for guidewire exchange is more common.
Conventional over-the-wire angioplasty catheters, with a guidewire lumen extending their entire length, permit simple guidewire exchange. During angioplasty procedures, the guidewire tip may become damaged, may be needed of a different type of guidewire or may need to be reshaped to complement the patient""s vasculature. The guidewire exchange procedure is readily accomplished with such a conventional over-the-wire catheter. However, with the rapid-exchange type catheter of U.S. Pat. No. 4,762,129, guidewire exchange requires complete removal and reinsertion of both the guidewire and the angioplasty catheter; thus, defeating the original goal of expedient advantage of the rapid-exchange catheter.
Another disadvantage of the rapid-exchange catheter is backbleeding. While the guidewire is being manipulated to select the target vessel or to cross the culprit lesion, the Tuehy-Borst adapter must be loosened. This, in turn, permits backbleeding to occur.
Accordingly, there is a need for an angioplasty catheter that permits rapid-exchange of the catheter like a monorail system, and easy exchange of the guidewire like the conventional over-the-wire system. There is also a need for a catheter that will permit the user to select the mode of usage between the rapid-exchange and the over-the-wire systems.
In accordance with one aspect of the present invention, there is provided an angioplasty catheter comprising a catheter shaft having a proximal end and a distal end, an angioplasty balloon attached to the shaft at the distal end, a balloon inflation lumen extending through the shaft and communicating with the interior of the balloon, and a guidewire lumen extending through the shaft and through the balloon for receiving a steerable guidewire, wherein the guidewire lumen has a proximal opening at the proximal end of the shaft for insertion of a guidewire into the lumen, and a side port for insertion of a guidewire into the lumen through the side wall of the catheter shaft, the side port located distally of the proximal opening, the side port comprising guidewire directing means for permitting a guidewire to extend through the side port distally into the guidewire lumen and exit through the distal opening at the balloon catheter tip; while preventing a guidewire from extending through the side port proximally in retrograde fashion into the guidewire lumen. In one embodiment, the side port is located adjacent to and proximally of the balloon. In another, the side port is located proximally of the balloon within about 35 cm of the balloon. In another variation of this catheter, the side port has proximal and distal ends, and the distal end of the side port is defined by a cut into the guidewire lumen extending generally transversely with respect to the length of the catheter shaft. Preferably, the proximal end of the side port is a cut tapering proximally and outwardly from the distal end of the side port. In another variation of the foregoing catheter, the proximal end of the side port is a cut extending through the guidewire lumen extending proximally from the distal end of the side port. In a preferred embodiment, the guidewire lumen has an outside wall and the guidewire directing means comprises a guide flap having a proximal end and a distal end, the guide flap attached at its proximal end to the outside wall, with the distal end of the guide flap tapering into the guidewire lumen, and where the distal end of the guide flap is not attached to the outside wall so that a guidewire inserted distally through the side port passes over the distal end of the guide flap and into the guidewire lumen. Preferably, the guide flap is relatively flexible in comparison to the outside wall of the guidewire lumen on the distal side of the side port.
In still another variation of the catheter discussed above, the first side port is within 35 cm of the proximal end of the shaft, preferably within 30 cm, and more preferably within 20 cm.
One embodiment of the invention further comprises a perfusion opening communicating with the interior of the guidewire lumen, the perfusion opening located between the side port and the balloon.
Another aspect of the present invention is a system for performing angioplasty, comprising an angioplasty catheter having a catheter shaft, a proximal end, a distal end, an inflatable balloon at the distal end, and a guidewire lumen extending from the proximal end to the distal end, the guidewire lumen having a proximal opening and a distal opening and adapted to receive a guidewire extending the entire length of the guidewire lumen, a side port in the catheter shaft providing an opening into the guidewire lumen, the side port being located proximally of the balloon between the proximal opening and the distal opening, and a guidewire extending from outside the catheter shaft, distally through the side port, and out of the distal opening. Preferably, the side port is located within 40 cm of the balloon, more preferably within 30 or 25 cm of the balloon. In one embodiment, the side port is located inside a patient on whom an angioplasty procedure is being performed.
The present invention also includes a method for exchanging angioplasty catheters while performing angioplasty, comprising the following steps. The guidewire may be pre-loaded in the balloon catheter, before both are introduced into the guiding catheter, by inserting the distal tip of the guidewire through the side port from outside into the guidewire lumen, advancing it distally through the balloon, and coming out of the distal opening of the balloon catheter. Alternately, with the guiding catheter properly engaged in the coronary artery, the method comprises introducing a guidewire into the guiding catheter through the Tuehy-Borst adaptor (if necessary, the guidewire tip positioned inside the vascular system), deploying a balloon angioplasty catheter of the type discussed above over the proximal end of the guidewire, so that the proximal end of the guidewire extends inside the distal guidewire lumen in a retrograde fashion through the balloon, the proximal end of the guidewire coming out through the side port, thus exiting out of the guidewire lumen, while the position of the distal tip of the guidewire is maintained in a fixed position in the patient. In both methods of deploying the balloon catheter of the type being discussed, the balloon catheter shaft and the guidewire are both inside the guiding catheter lumen, but the guidewire proximal to the location of the side port is outside the balloon catheter lumen, side by side with the balloon catheter shaft, and the guidewire is inside the balloon catheter lumen on the distal side of the side port. The steps of exchanging balloon catheters consist of removing the first balloon catheter from the proximal end of the guidewire while maintaining the tip of the guidewire in the location (in the vascular system if necessary) where the operator intended, positioning a second balloon catheter according to the present invention over the proximal end of the guidewire extending proximally through the guidewire lumen, through the balloon segment and the proximal end of the guidewire, exiting through the side port of the balloon catheter, and then advancing the second balloon catheter over the pre-positioned guidewire into the vascular system.
The present invention also includes a method of exchanging a guidewire during an angioplasty procedure using the catheter of the present invention, comprising the steps of positioning a guidewire in the vascular system of a patient, providing the catheter over the guidewire so that the proximal guidewire extends proximally from the distal tip of the catheter and through the side port, advancing the catheter along the guidewire into the vascular system, removing the guidewire while maintaining the catheter in the vascular system, and inserting a second guidewire into the catheter distally through the proximal opening, through the guidewire lumen past the side port, through the balloon, and out of the distal end of the catheter.
A further method encompassed by the present invention is a method for performing balloon angioplasty, comprising the steps of providing a balloon angioplasty catheter having a catheter shaft having proximal and distal ends, a guidewire lumen through the shaft, an inflatable balloon on the catheter shaft at the distal end of the catheter, and a side-port located between the proximal end of the catheter and the balloon communicating with the interior of the guidewire lumen, inserting the catheter into a patient and blood vessel over a guidewire in the guidewire lumen, so that the guidewire extends out of the distal end of the balloon catheter while selecting a lesion, inflating balloon with the guidewire in place partially withdrawing the guidewire proximally so that the guidewire does not obstruct the side port, and inflating the balloon in a stenosis while the guidewire is partially withdrawn, so that blood can flow into the side port, distally through the guidewire lumen, and out of the distal end of the catheter while the balloon is inflated.